Typically, shoelaces are used for securely attaching a shoe to a foot. Laces are cheap, easy to replace, and are particularly preferred for sports shoes, since their soft composition poses little risk of injury. Each time a shoelace is tied, however, care must be taken to ensure that the shoe is not too loose or too tight on the foot. Further, during wear, shoelaces can loosen or become untied.
Several alternatives to shoelaces are known from the prior art, such as hook and loop fasteners, such as the VELCRO® brand sold by Velcro Industries B.V. Other fasteners such as buckles, which extend over the instep, are also known. Hook and loop connections can be easily and quickly operated, but they wear out after a short time and require a considerable amount of attention to attain the desired tension when securing the shoe to the foot. Also, the corresponding surfaces of the fastener must be aligned correctly for a stable connection. Similarly, buckles, which have a predetermined closing movement, tend to be simple to operate; however, buckles are often excluded on shoes, in particular sports shoes, since they present a considerable risk of injury to other athletes because of the hard materials from which they are typically made. Further, they are only incrementally adjustable.
Many different closure constructions are also known from ski boots. U.S. Pat. No. 4,677,768, the disclosure of which is hereby incorporated herein by reference in its entirety, discloses a system where two levers are arranged inside each other at the end of the shaft of the ski boot, which is directed to the knee at a height corresponding approximately to the calf. The levers are used to tighten two cables. An upper cable pulls rigid anterior and posterior plastic shells together in the area of the calf and thereby closes the ski boot. The second cable pulls a free floating pressure element provided in the interior of the ski boot in the direction of the foot at an angle nominally at a midpoint between horizontal and vertical to reduce relative movement of the foot inside the boot.
The construction described above for ski boots cannot easily be transferred to shoes that are used for walking or running, since such shoes include flexible uppers, unlike a ski boot, which has a rigid outer shell. Typically, the upper in a shoe is made, for example, from leather or a soft synthetic material so that movement of the foot is not hindered while walking. In contrast to a ski boot, any closure system for a shoe having a flexible upper has to take these movements of the foot into consideration.
It is, therefore, an object of the present invention to provide a shoe with a flexible upper which can be easily, comfortably, and quickly retained on the foot, without limiting the freedom of motion of the foot necessary for unimpaired walking or running.